Relay



8- 13, 1959 w. F. oownu: 2,900,472

Raw:

Filed July 22, 1957 2 Shoots-Sh! 1 A118? 18, 1959 w. F. DQWDLE I2,900,472

RELAY- Til ed July 22. 1957 2 Shoots-Shut 2 United States Patent RELAYWalter F. Dowdle, Lincoln, Ill., assignor to Essex Wire Corporation,Fort Wayne, 1nd.

Application July 22, 1957, Serial No. 673,246 2 Claims. (Cl. 200-87)This invention relates to an improved construction of an electromagneticrelay and more particularly to an 1mproved contact actuator forelectromagnetic relays. The method of assembling electromagnetic relaysdisclosed herein is being claimed in application Serial No. 772,647,filed October 23, 1958, which is a division of the present application.

A principal object of this invention is to provide a relay which isrugged, simple, inexpensive to manufacture, assembly, and adjust.

Another object is to provide a relay which can be accurately anduniformly adjusted during its process of manufacture and assembly andbefore it has been completely assembled.

Other objects and advantages of the invention w1ll appear in thefollowing description and appended claims, reference being had to theaccompanying drawings, in which:

Figure 1 is a side elevation of a relay embodying the invention.

Figure 2 is a top plan view of the relay.

Figure 3 is a side elevation similar to Figure 1 showing the armature inthe attracted position.

Figure 4 is a perspective view of the insulating bracket.

Figure 5 is a side view of the contact spring.

Referring to the drawing, the electromagnetic relay there illustratedand embodying the features of the present invention includes a frameformed from magnetic material and having a base portion 11 and a legportion 12 bent at right angles to each other. Mounted on the frame baseportion 11 is a coil 13 having a core 14 which is secured to the framebase portion 11 by screw 15. Core 14 is split at its end 16 toaccommodate a shading washer 17. For D.C. operation of the coil 13, thecore 14 need not be split and the shading washer 17 may be omitted.

An armature 18 extends through an opening 19 providing in the frame legportion 12 for movement from an unattracted position shown in Figure 1to an attracted position shown in Figure 3 when the coil 13 isenergized. In the unattracted position, the armature 18 is biasedagainst a stop portion 20 integral with the frame leg portion 12 byspring 21 which is secured to the extending {end of armature 18 and to alug 22 stamped out of the frame leg portion 12.

Secured to the frame leg portion 12 by rivets 23 are the feet 24A of aninsulating block 24 having a shelf portion 25 extending over thearmature 18. Mounted upon the insulating Hock 24 and extending over theshelf 'portion 25 are two flexible contact springs 26 carrying movablecontacts 27 to engage with and disengage from the fixed contacts 28located on the shelf portion 25. Circuit connections to suitableconductors may be made by means of screws (not shown) threaded into theterminals 29 which are secured to the contact springs 26 and the fixedcontacts 28.

The free ends of the contact springs 26 extend beyond the insulatingblock shelf portion 25 and are engaged 2,900,472 Patented Aug. 18, 1959by arm 30 of an insulating bracket or actuator 31 having a base 31Aattached to the armature 18 by rivets 32 to disengage the movable andfixed contacts 27 and 28 in the unattracted position. The contactsprings 26 are preformed or bent to produce a desired contact force orpressure between the movable and fixed contacts in the attractedposition. In the unattracted position, spring 21 biases the armature 18against the stop portion with a greater force than the biasing force ofthe contact springs 26.

Energization of the coil 13 causes the armature 18 and the arm 30 tomove toward the core end 16. As the armature approaches the attractedposition, the movable contacts 27 engage the fixed contacts 28 and thearm 30 separates from the contact springs 26. In the attracted position,the contact pressure between contacts 27 and 28; is determined solely bythe biasing force of the contact spring 26. The biasing force of thecontact springs 26 aids the movement of the armature 18 in its initialmovement toward the attracted position.

After deenergization of the coil 13, the armature l8 and the arm 30 arereturned to the unattracted position by spring 21. Because of theseparation between the arm 30 and the contact springs 26 in theattracted position, the armature 18 travels a given distance before thearm 30 strikes the contact springs 26. The impact force of arm 30 uponthe contact springs 26 is advantageous in that it breaks any contactweld which may have formed between contacts 27 and 28.

By reason of the present construction, the assembly and adjustment ofthe relay has been greatly simplified. No bending or forming operationsare required during onafter assembly of the relay to adjust the contactpressure, the contact gap, or the contact closing voltage to withinnarrow specified limits. By eliminating the manual adjustments normallyrequired, the manufacturing cost of the relay is considerably reduced.

The only adjustment necessary to obtain consistent contact pressures isperformed before assembly of the relay. Before the contact spring 26 issecured to the insulating block 25, its contact carrying end is bent toa specified angle A relative to the opposite end as illustrated inFigure 5. It is a relatively simple matter to manufacture the bentcontact spring 26 with a high degree of uniformity and a correspondinghigh degree of uniformity in the contact pressure is obtained.

A consistent contact closing voltage is similarly obtained with noadjustment required during assembly of the relay by manufacturing theframe 10 with the protruding end of the stop portion 20 located at aspecified distance from the base portion 11. In the assembled relay, theprotruding end of the stop portion 20 will be separated by a requireddistance from the end 16 of the core 14 which is also easilymanufactured to have a specified length. Thus the gap between thearmature 18 and the core end 16 is easily maintained within narrowlimits to provide the relay with armature operating and contact closingvoltages within equally narrow limits.

The required separation between the movable and fixed contacts 27 and 23in the unattracted position is obtained by employing a selectedinsulating bracket 31 having an arm 30 of the height H necessary toprovide the required contact separation. The selected bracket 31 havingan arm 30 of the required height H is preferably secured to the armature18 after the remainder of the relay is assembled. The required height Hof the arm 30 may be determined by measuring the separation between thecontactsprings 26 and the armature 18 in the unattracted position beforethe bracket 31 is attached. The required bracket arm 30 will have aheight greater than the separation by a fixed amount equal to thedesired contact separation.

Because the distance of armature travel between the attracted andunattracted positions has a uniform value, the required bracket armheight H may also be determined by measuring the separation between thecontact springs 26 and the armature 18 in the attracted position beforethe bracket 31 is attached. The bracket arm 30 is selected to have aheight H less by a fixed amount than this separation to provide both aconsistent separation between contacts 27 and 28 in the unattractedposition and a consistent gap between the arm 30 and the contact springs26 in the attracted position.

The contact separation in the unattracted position is generally not verycritical and it has been found that the separation between armature 18and the contact springs 26 need not be actually measured, but instead aselected bracket 31 is inserted between the armature 18 and the contactsprings 26. By visual inspection only, it can be readily determined ifthe selected bracket provides the desired separation between the contactsprings 26 and the arm 30 in the attracted position. Furthermore, thebracket 31 may be selected from a group of brackets 31 having arms 30and varying in height by increments of approximately .015 inch.

Figure 4 illustrates means by which the arms 30 of varying height may bereadily distinguished. The brackets 31 are initially molded with allarms 30 having a specified height. On one side of the arms 30 isprovided a number of indentations or grooves 33 having their bottomportions located at dilferent specified distances from thearmature-engaging surface of the bracket 31. When a portion of thespring-engaging surface is removed to provide an arm 30 of a specifiedheight, the number of detents 33 remaining indicates the height of thearm 30.

While the invention has been illustrated and described in its preferredembodiment and has included certain details, it should be understoodthat the invention is not to be limited to the precise details hereinillustrated and described since the same may be carried out in otherways falling within the scope of the invention as claimed.

What is claimed is:

1. In a relay of the type comprising a magnetic frame having a baseportion and a leg portion extending at approximately right angles tosaid base portion; a magnetic core joined at one end with said baseportion to extend in generally parallel, spaced relation with said legportion; a coil surrounding said core; a magnetic armature pivotallysupported on said leg portion for switch operating movement toward andaway from the other end of said core; means biasing said armature in adirection away from said core; a block of insulating material having afoot portion secured to said leg portion to support the block and havinga shelf portion disposed substantially at right angles to said footportion to extend over said armature; a fixed contact supported on saidshelf portion; a cantilever spring fixed at one end to said block andhaving its free end extending beyond the extending end of said shelfportion tooverlie the free end of said armature; said cantilever springbeing biased in a direction toward said fixed contact and carrying amovable contact arranged to engage said fixed contact; a contactactuator of insulating material secured to the free end of the armatureadjacent the free end of said cantilever spring for engagement therewithwhen said armature is biased away from said core; and said armaturebiasing means having a force greater than the force of said cantileverspring biasing means to disengage said contacts when said armature isnot attracted by said core; the improvement in said contact actuatorwherein said contact actuator comprises an L-shaped bracket having anarm for engaging said cantilever spring and a base disposed atsubstantially right angles to said arm, said base being disposed uponand secured to the free end of said armature to permit securing of saidbracket to said armature after the remainder of the relay is assembled,said arm having a selected height providing a desired separation betweenthe free end of said cantilever spring and said arm when said armatureis attracted by said core; and said arm being provided with a pluralityof indentations having bottom portions located at difierent distancesfrom the end of said bracket arm adjacent said armature to indicate theheight of said bracket arm.

2. In a relay of the type of having a magnetic core structure; anenergizing winding carried on said core structure; an armature supportedby said core structure and movable between magnetically attracted andunattracted positions; a cantilever spring supported at one end on saidcore structure and having its free end extending over said armature; arelatively fixed contact sup ported by said core structure; saidcantilever spring being biased in a direction toward said fixed contactand carrying a movable contact arranged to engage said fixed contact;and a contact actuator secured to the armature adjacent the free end ofsaid cantilever spring for engagement therewith when said armature is inits unattracted position; the improvement in said contact actuatorwherein said contact actuator comprises a substantially L-shaped brackethaving an arm for engaging said cantilever spring and a base extendingat substantially right angles to said arm; said base being secured onone side of said armature; said arm having a selected height providing adesired separation between the free end of said cantilever spring andsaid arm in the attracted position of said armature; and said arm beingprovided with a plurality of indentations having bottom portions locatedat ditferent distances from the end of said bracket arm adjacent saidarmature to indicate the height of said bracket arm.

References Cited in the file of this patent UNITED STATES PATENTS2,121,851 Barrett June 28, 1938 2,391,222 Blattner Dec. 18, 19452,421,641 Obszarny June 3, 1947 2,517,052 Swinehart Aug. 1, 19502,526,455 Bonanno Oct. 17, 1950

